1. Diameter End-to-End Security: Keyed Message Digests, Digital Signatures, and Encryption draft-korhonen-dime-e2e-security-00 Jouni Korhonen, Hannes Tschofenig Dime WG, IETF#83

2. Overview Two aspects: Authentication and Key Exchange Actual AVP protection. Requirements. Strawman solutions proposal.

3. Requirements Provide end-to-end security properties to Diameter on top of existing hop-by-hop security model. Works with existing request routing and through agents that might modify parts of the message (like rearrange AVPs). Decouple key management from actual e2e AVP security protection. Offer both integrity and confidentiality protection. Easy to integrate into existing Diameter applications (integrity protection).

4. Strawman Proposal in draft-korhonen-dime-e2e-security-00 This solution focuses on protecting Diameter AVPs. To offer the functionality two AVPs are defined: Signed-Data (octet string) for integrity protection of one or more AVPs. Encrypted-Data (octet string) for confidentiality protection of one or more AVPs. Re-use existing security mechanisms. A few choices available including: CMS XML DSIG/Encryption JSON We use JSON due to ease of implementation: JSON Web signature (JWS) for integrity protection JSON Web Encryption (JWE) for confidentiality protection Not tied to a specific Diameter application. Authentication and key management is not part of this proposal: Likely that “one size fits all” approach will not work due to different deployment environments

5. Signed-Data AVP The AVP carries JSON Web Signature (JWS) of one or more of AVPs. Each protected AVP is hashed and the hash is included into the JWS payload. Hashed AVPs are linked to “originals” using their AVP Code. If there are multiple instances of the same AVP, you hash them all and do one by one verification -> allows for rearranging AVPs and detection of addition/removal/modification of AVPs. Both JWS Payload and signature use the same hash algorithm of the cryptographic algorithm indicated in the JWS Header. Can be included into existing Diameter applications.

6. Encrypted-Data AVP The AVP carries JSON Web Encryption (JWE) data structure and the JWE Payload embeds of one or more protected AVPs. Cannot be used with existing Diameter applications since encrypted AVPs are embedded inside the Encrypted-Data AVP(s).

7. Error Handling Transient failures DIAMETER_KEY_UNKNOWN - A Signed-Data or an Encrypted-Data AVP is received that was generated using a key that cannot be found in the key store. To recover a new end-to-end key establishment procedure may need to be invoked. Permanent failures DIAMETER_DECRYPTION_ERROR - This error code is returned when an Encrypted-Data AVP is received and the decryption fails for an unknown reason. DIAMETER_SIGNATURE_ERROR - This error code is returned when a Signed-Data AVP is received and the verification fails for an unknown reason.

8. Questions? Comments?